Flotation apparatus



F. E. MARCY.

FLOTATION APPARATUS. I APPLICATION FILED MAR-24,1919. RENEWED OCT. 13, 920.

Patented July 5, 1921.

3 SHEETS-SHEET 1.

I 5y ATTORNE).

F. E. MARCY.

FLOTATIO APPLICATION man MAR. 24, 19x9. RENEWED ocr.13.1920.

N APPARATUS.

Patented July 5, 1921.

3 SHEETS-SHEET 3.

UNITED STATES PATENT OFFICE.

FLOTA'IION APPARATUS.

Application filed March 24, 1919, Serial No. 284,700.

To all whom it may concern:

Be it known that I, FRANK E. MARCY, a citizen of the United States, residing at Salt Lake City in the county of Salt Lake and State of lltah, have invented certain new and useful Improvements in Flotation Apparatus, of which the following is a full, clear, and exact description, reference be ng had to the accompanying drawings, forming a part hereof.

The present invention is directed to improvements in flotation apparatus or that involved in the concentration of ores by the flotation process. As well understoodin the art, concentration of ores by flotation 1s brought about by mixing finely ground ore and gangue with water in the proportion of about four parts of water to one of ore, and agitating the resulting pulp with a suitable oil having a preferential aflinity for the metalliferous matter over the gangue. The oil when agitated in water becomes a frothing agent and a conveyer for the sulfid mineral. The necessary flotation of the oiled mineral particles is effected through the agency of air bubbles to which the sulfid particles become attached, the accepted theory being that these particles attach themselves on the outside of the air bubble. In some cases the flotation apparatus comprises a box provided with revolving impellers that are submerged in the pulp, and in their revolution they cause a thorough mixture of the frothing agent with the pulp. At the same time air is brought into the mixture by the rapidly revolving impellers causing innumerable air bubbles to be formed. which, as well understood in the art, have the property of supporting the oiled sulfid particles and causing them to accumulate on the surface of the pulp. There is another class of apparatus whose main function is to supply air to the pulp subjected to previous agitation and oiling. These apparatus are usually in the form of elongated rectangular tanks provided with a porous bottom generally of canvas. through which air under pressure is forced into the pulp where it immediately forms into bubbles which become carriers of the mineral particles. There is a third class of apparatus employing a very soluble frothing agent not requiring previous agitation or beating. other than the agitation caused by the air and bubbles that come through the porous bottom.

Specification of Letters Patent.

Patented July 5, 1921.

Renewed October 13, 1920. Serial No. 416,774.

The present invention is particularly directed to the type of apparatus employing the porous or canvas bottom and has for its object to overcome certain objections inherent in such a bottom. A canvas bottom is generally made of three to five ply canvas ducking, and is so thick that a large amount of power and energy is lost in forcing the air through it, such a bottom being a power destroyer of the worst type and producing a tremendous amount of friction. *or example, when air passes through canvas its pressure is immediately reduced to the pressure within the pulp, or to the static head in the tank, to-wit, approximately .45 of a pound per square inch for each foot in height, so that in a flotation apparatus having a static head of three feet of pulp the actual pressure of air at the bottom of the cell or tank is three times .45 or about 1.35 pounds, to maintain which it is necessary to have an air pressure under the blanket of nearly six pounds to the square inch. There is therefore a loss of 4.65 pounds to the square inch, and a consequent proportionate loss of power. Vere there no loss in passing through the porous bottom it would require only 1.35 pounds to do the work instead of six pounds. It is of course true that no bottom could be made in which there was notsome friction. A theoretically frictionless bottom would be a plate having smooth, round holes, but such a plate is not practical, because the holes which must necessarily be made small soon become blinded with sand. So long as the small holes operate they are economical as to pressure required, and result in the production of uniform bubbles. In practice, it has been found that bubbles onehalf inch in diameter are very effective as carriers of mineral, and it has also been found that it is not necessary to have the openings closer than the size of an eifective bubble. In a canvas or equivalent porous bottom the air necessarily discharges in many directions. many of the air jets either uniting. or causing effective bubbles to collapse. Air openings of broken spacing and with sufiicient capacity are equally eiticient as the canvas bottom.

By my invention the objections inherent in a canvas or porous bottom are overcome. my improved bottom having not only a clear opening for the passage of the air therethrough. but being at the same time provided with suitable means for preventing 010g ging of the opening; or, if the opening should become clogged the sand may be readily loosened and the opening cleared during the concentrating operation. A further object of the invention is to dispense with the necessity of a sloping bottom for the flotation tank, thereby operating under a constant and uniform hydraulic head and dispensing with the use of battles, and with the use of controlling valves for adjusting the air pressures to the varying hydraulic heads necessarily present in tanks having sloping bottoms. A further object is to economize power by the lowering of the air pressure necessary to generate the bubbles; to prolong the life of the bottom as compared with canvas or other porous bottoms; to re duce the cost of upkeep; to produce a better and more effective type of air bubble, said bubble being projected in a direct line into the pulp by reason of the uniform, small and smooth opening employed, said opening being kept clean at all stages of the operation. The advantages of the invention will be apparent from the following detailed description in connection with the accompanying drawings in which Figure 1 represents a diagrammatic isometric view of a flotation tank or cell showing one form of my invention applied thereto; Fig. 2 is a longitudinal vertical middle section through the bottom portion of the tank and through the air box or compressed air chamber; Fig. 3 is a transverse vertical middle section of the same; Fig. 4 is an enlarged top plan of one-half of the tank with parts broken away; Fig. 5 is an end view of one of the cleaning pins shown in connection with the opening of the bottom traversed by the ')in; Fig. 6 is a vertical sectional detail through the tank bottom and opening thereof traversed by a pin showing the grid to which the pin is secured; Fig. 7

is an end view of a modified form of cleaning pin; Fig. 8 is an elevation thereof shown in connection with the grid and tank bottom; Figs. 9 and 10 are similar views of another modification of cleaning )in; Fig. 11 is a view at right angles to ig. 10; Figs. 12 and 13, 14 and 15, 16. and 17, 18 and 19, 20 and 21, and 22 and 23Qare each respectively views similar to Figs. 7 and 8 showing still further modifications of cleaning pins; Fig. 21 is a plan of a cleaning member in the form of a tongue or plate. the same traversing an air slot in the tank bottom; Fig. 225 is a vertical cross-section of Fig. 24: Figs. 26 and 27 are views similar to Figs. 24 and 25 showing a modified form of cleaning tongue; Fig. 28 is a view similar to Fig. 2 showing cleaning pins disposed at an incline to cause a general movement or migration of the sands toward the discharge end of the tank; Fig. 29 is a diagrammatic cross-section of a tank with a V-shaped perforated bottom having vertical cleaning pins; Fig. 30 is a diagrammatic isometric cross-section of a tank having a U-shaped perforated bottom with vertical cleaning pins; and Fig. 31 is. a diagrammatic isometric View showing a modified contrivance for reciprocating the cleaning pins.

Referring to the drawings, and for the present to F igs. 1 to 6 inclusive, T, represents a conventional flotation cell or tank having a feed end a for the pulp and a discharge end for the sands or tailings, and side overflows c for the concentrates as well understood in the art. In lieu of the usual canvas or porous bottom employed in this type of apparatus, I substitute a perforated bottom or plate 1, the same containing a plurality of holes or openings 0 preferably circular, said openings being tranversed by pins 2 of smaller cross-section so as to leave a clearance all around the pin for the passage of air from the bottom air box or compressed air chamber 3 to which air (or other gas) under pressure is supplied from any suitable source by a feed pipe 4. The pins 2 are secured to or carried by a grid or equivalent perforated support 5 disposed in the air box beneath the perforated cell bottom 1, the sides of the grid resting on the cams 6, 6, disposed on the transverse parallel rockshafts 7, 7, said shafts extending across the air box at each end thereof, the projecting ends of the shafts on one side of the tank being provided with hand levers 8, 8, connected by a link 9 pivotally secured thereto. By seizing either lever 8 and oscillating the same, a rocking motion will be imparted to the rock-shafts and to the cams secured thereto. the cams in turn imparting a vertical reciprocating movement to the grid 5 and to the pins 2 projecting therefrom. the throw of the cams in the example before us being suflicient to project the pins substantially half their length through the plate 1 on the upstroke of the grid. As stated above, there is left a clearance around the pin 2 (which is permanently in the opening 0) for the passage of the air from the air box into the tank (Figs. 5 and 6) this clearance, for an opening of one-half inch in diameter being by Way of example, .015 of an inch, that is to say. the diameter of the pin is about .03 of an inch smaller than that of the opening which receives it. The pins as well as the walls of the openings formed in the cell bottom should be perfectly smooth so that not only may the air pass freely through the clearance into the tank, but the openings will lend themselves to ready cleaning by the reciprocating movement of the pins therethrough. The amount of clearance between the pin and the wall of the opening which receives it may of course be varied, depending on conditions to be met and on the character of ore treated.

The operation is the same as in the conventional flotation apparatus of this type. The compressed air is forced through the openings 0 of the tank bottom around the pins, the air penetrating the pulp in the tank in the form of jets forming air bubbles which bring about the flotation of the oiled mineral particles attaching themselves thereto, the resulting froth or concentrates being drawn off by way of the overflows 0, whereas the sands or tailings are drawn off by way of the discharge 6. The advantages of a perforated bottom such as 1 over the usual porous or canvas bottom are (1) the saving of power by reason of reduction of friction in the passage of the air through the perforations o; (2) a freer and more direct flow of the air into the pulp; (3) a more constant and uniform direction of discharge of the air into the pulp, thereby reducing the tendency of effective bubbles uniting and subsequently collapsing; (4) increased efliciency or tank output; (5) the provision for keeping clean the perforations without the necessity of-stopping operations, it being not only practical, but indeed desirable, to reciprocate the cleaning pins 2 from time to time during the flotation operation so as to keep the perforations clean and free to the passage of the air therethrough. The walls of the openings 0 and the peripheries of the pins being smooth, the mere reciprocation of i the pins is sufficient to loosen any sand which has been packed around the pins, so that blinding of the air passages by the sands is practically impossible. Other advantages of a perforated cell bottom provided with cleaning pins are sufiiciently set forth in the statement of the objects sought by the invention and need not be here repeated.

The invention necessarily and obviously includes within its scope a large variety of structures, a few of which will now be briefly referred to. In Figs. 7 and 8 is shown a cleaning element or pin 10 fitting snugly and yet free to reciprocate in the opening of the bottom 1, the said pin being formed with diametrically opposite longitudinal peripheral grooves 11, 11, extending normally below the bottom 1 and into the air tank 3, said grooves serving to conduct the air in the form of jets into the tank. These grooves take the place of the clearance formed around the pin 2 in the form first described (Figs. 5, 6). In Figs. 9, 10, and 11 is shown a pin 12 with warped peripheral grooves 13, 13, meeting at a point in the air box, the air jets therefrom being projected at an angle to the tank bottom and in the general direction of the discharge end of the tank whereby the sands on resting on the bottom are caused to move or migrate toward said discharge end. Such a construction dispenses with the usual sloping bottom to be found in this type of apparatus in assisting the sands toward thedischarge end, and likewise dispenses with the baflies used in conjunction with a sloping bottom on account of the varying hydraul'ic head to which a sloping bottom gives rise. In Figs. 12 and 13 is shown a pin 14 provided with a plurality of longitudinal peripheral ribs t which form suitable passage-ways or ducts d for the passage of the air into the tank. In Figs. 14 and 15 is shown a pin 15 mounted loosely on the grid 5 so as to be free to rotate about its axis, said pin being provided with a spiral peripheral groove 16 whereby as the same is traversed by the airy it will tend to rotate the pin and thus keep the main passage-way around the pin clean. In Figs. 16 and 17 is.shown a pin 17 which fits snugly the opening in the bottom but with sufiicient looseness to permit of free reciprocation of the pin through the open ing, the walls of the latter being provided with longitudinal diametrically opposite grooves 18, 18, for the passage of the air. In Figs. 18 and 19 is shown'a pin 19 on the order of the pin 2 except that the same is polygonal in crosssection (square in this case) traversing a corresponding opening 0 in the cell bottom. In Figs. 20 and 21 is shown a pin 20 with a bottom conical head 20 whereby with a full throw of the operating levers 8 said head will enter the corresponding depression k formed around the opening 0 in the bottom and close up the opening, thereby preventing the pulp from leaking into the air box. In Figs. 22 and 23 is shown a pin 21 formed with a spiral groove 22 (on the order of the groove 16 in E'g.-l5) which tends to rotate the pin. the {fatter being provided below the groove wit 1 a collar or cleaning ring 23 adapted to snugly engage the walls of the opening 0 when the grid 5 is reciprocated, thereby thoroughly and positively cleaning the opening, and permitting the air to flow freely therethrough when the grid is depressed to its lowest or normal position.

In the forms so far described we have been dealing with cleaning pins or elements to which the designation pin" is strictly appropriate; but in Figs. 24 and 25 is shown a modification in which is employed a plate or tongue 24 traversing freely an oblong slot 8. of the bottom, the tongues I pin, the air is either delivered in the form of a hollow cylinder (Figs. 5, 6,) or hollow prism (Figs. 18, 19), or as a solid prism or pencil the cross-section of which necessarily depends on the shape of the duct through which the air is projected (Figs. 7, 8, 12, 13, 16, 17

In connection with Figs. 9, 10 and 11 it was pointed out that the inclined projection of the air jets toward the discharge end of the tank caused the sands on the bottom to be moved or caused to migrate in the direction of the sand discharge without resorting to a-sloping bottom for the tank. In Fig. 28 is shown another method of accomplishing the same result. In this modification resort is had to a bottom 1 in which the axes of the perforations 0" are parallel and inclined upward toward the discharge end of the tank, the apparatus being provided in this case with a grid 5' carrying inclined pins 2 traversing the perforations or openings 0", the grid (and its pins) being constrained to reciprocate along inclined lines parallel to the axes of the perforations by means of inclined guide-rails 30 traversed by a roller 31 on each side of the grid, the parts referred to being shown more or less con.- ventionally and in a sense diagrammatically, as the desired construction may be arrived at by the skilled mechanic without further details. It will be seen from this figure that the air jets escaping at an incline into the tank will cause the sands m to move or advance toward the discharge end of the tank on a perfectly horizontal bottom.

I do not wish to be understood as limiting the application of the cleaning devices aforesaid to flotation cells having horizontal bottoms, as the same may with equal propriety and effectiveness be applied'to sloping, V-shaped, or U-shaped bottoms. Thus, in Fig. "29 is shown a V-shaped perforated bottom B to which vertical cleaning pins 32 are applied, the tank T and its appurtenances being not unlike that shown in Fig. 1.

In this case the reciprocable grid 5 must necessarily be slightly modified to conform to the sloping sides of the bottom. In Fig. 30 is shown a tank T with a perforated U- shaped bottom B which is kept clean by the vertical pins 33 leading from a reciprocable grid 5" which is substantially the same as the grid 5 in the forms first described.

In the several apparatus above referred ,to the reciprocation of the grid and its ins is accomplished by means of cams carrie by rock shafts. It is apparent however that other means for reciprocating the grid might be resorted to. Thus, in Fig. 31 is shown a grid 34 secured to hangers or links 35 passing loosely through the tank bottom, the upper ends of the links being coupled to any suitable machine driven element, (not shown) capable of imparting vertical reciprocations to the links and to the grid. The reciprocations might even be imparted to the grid by hand, one operator at each end seizing two links and the two jointly lifting and then dropping the grid. There are many ways in which a cleaning motion, be it reciprocating or rota y or any combination of the two, can be imparted to the cleaning pins or their equivalents.

From the foregoing it is apparent that all the objects sought by the invention are attained thereby, the objections inherent in the prevailing canvas or porous bottom being entirely overcome. The apparatus is susceptible of considerable modification, not here shown or alluded to; and accordingly I do not wish to be restricted to the forms here illustrated, it being obvious that still other forms may be resorted to without departing from either the nature or spirit of the invention.

In the structures above described the cell bottom (or diaphragm between the tank and air box) is assumed to be of metal, but it is entirely feasible to have a bottom of glass with holes properly spaced. One method of making these holes would be to cast metal rods (or wire) in the glass and then etching out the rods leaving the walls of the resulting openings perfectly smooth. As to the size of the openings, that may be left to the judgment of the operator. I have already indicated the amount of radial clearance between the walls of a half-inch opening and its pin (.015 of an inch). In the case of grooves such as 11 (Figs. 7, 8,) or 13 (Figs. 9, 10, 11,) these may be from to inch across; the same with passages such as 18 in Figs. 16, 17. These dimensions however are merely by way of example and may be departed from. Neither do I wish to be limited as to the number of jet openings to a unit of surface, the object sought in all cases being to secure the necessary number of jets to accomplish the objects of the invention. Experiments have shown that one hundred (100) pins, each with two grooves (Figs. 7, 8,), to the square foot, are often ample in number. These may of course be varied at will. The advantages of the present invention over the prevailing forms of canvas and porous bottoms are manifest.

Having described my invention what I claim is:

1. .A flotation cell provided with a bottom having air inlet openings, and means within the confines of the openings forming suitable passageways with the walls thereof for the passage of air into the cell.

2. A flotation cell provided with a bottom having air inlet openings, and means within the confines of the openings spaced from the walls thereof and forming with said walls suitable passage-ways for the passage of air into the cell.

3. A flotation cell provided with a bottom having air inlet openings, and means within the confines of the openings forming suitable passage-ways for the free and unobstructed flow of air into the cell.

4; A flotation cell provided with a bottom having air inlet openings, and movable means within the confines of the openings forming suitable passage-ways for the free and unobstructed flow of air into the cell.

5. In a flotation cell, an air plate or diaphragm perforated at intervals, and cleaning devices in the perforations forming with the walls of the perforations suitable passage-ways for the influx of air into the cell.

6. In a flotation cell, an air plate or diaphragm provided at intervals with air inlet openings, and cleaning pins traversing the openings and forming with the walls thereof suitable passage-ways for the flow of the air into the cell.

7. In a flotation cell, an air plate or diaphragm provided at intervals with air inlet openings, and cleaning pins in the openings spaced from the walls thereof to form suitable passage-Ways for the flow of air into the cell.

8. In a flotation cell, an air plate or diaphragm provided at intervals with air inlet openings, cleaning pins in the openings forming with the walls thereof suitable passage-ways for the flow of air into the cell, and means for reciprocating the pins axially in the openings.

9, In a flotation cell, an air plate or diaphragm provided at intervals with air inlet openings, cleaning pins in the openings forming with the walls thereof suitable passage-ways for the flow of air into the cell, means for reciprocating the pins axially in the openings, and means on the pins for closing the openings and the passage-ways aforesaid.

10. A flotation cell having a suitable point of pulp discharge, a. perforated bottom for the passage of air into the cell, and means for directing the air jets in the general direction of the point of pulp discharge and causing the sands to migrate toward said point. i

' 11. A flotation cell having a suitable point of pulp discharge, a perforated bottom for the passage of air into the cell, and means for directing the air currents while traversing the perforations in the bottom, in the general direction of the pulp discharge and causing the sands to migrate in the same direction.

12. A flotation cell having a suitable point of pulp discharge, and a bottom having air delivery openings with their axes inclined upward in the general direction of the pulp discharge.

13. A flotation cell provided with a bot- 65 tom having air openings disposed with their axes parallel to one another and operating to deliver into the cell air jets in direct lines Without interference from one another and out of range of the axes of the openings.

14. A flotation cell provided with a bottom having a plurality of openings operating to discharge into the cell air or gas in fixed inclined directions.

15. A flotation cell provided with a bottom having a plurality of openings operating to discharge into the cell air or gas under pressure, in fixed inclined and parallel directions.

16. In combination with a flotation cell provided with a bottom having a plurality of air openings, an air chamber below the bottom, a perforated pin support in said chamber, pins on the support extending into and permanently maintained in the openings of the cell bottom, and means for reciprocating said support and pins carried thereby for cleaning the air openings at any stage of the concentrating operation.

17. In combination with a flotation cell provided with a bottom having a plurality of air openings, an air chamber below said bottom, a grid in the air-chamber, pins on the grid permanently traversing the openings of the cell bottom, and means outside the cell under the control of the operator for imparting reciprocating movements to the grid and to .the pins for cleaning the openings aforesaid.

18. A flotation cell provided with an air plate having openings, pins traversing said openings and spaced from the walls thereof to form passageways for the air, cleaning rings on the pins normally positioned outside the openings, means for moving said pins to cause the rings to enter the openings, the di? 10 ameter of the rings being suflicient to cause the peripheries thereof to rub the walls of the openings and thereby clean the walls with a movement of the pins.

19. A flotation cell provided with a bottom 110 having direct air inlet openings for the passage of air into the cell, and positive means in the openings for cleaning the openings and forming passage-ways with the walls thereof during the concentrating operation.

20. In a flotation cell, an air plate provided with a plurality of inclined parallel air passage-ways elongated in the line of the axis of the passage-Way.

21. In a flotation cell provided with an air 120 plate forming the bottom of the cell, said plate having a plurality of openings, and means for passing air through the openings into the cell and simultaneously causing the sands on the bottom of the cell to advance 125 in a given direction in response to the air curreplts discharged from said openings into the ce 22. In a flotation cell having a suitable point of feed and a point of tailings dis- 130 charge, and provided with an air plate forming the bottom of the cell, said plate having a plurality of,openings, and means for passing air through the openings into the cell and simultaneously causing the sands on the bottom to advance in the general direction of the point of tailings discharge in response to the currents discharged from said openings into the cell.

23. In a flotation cell, a bottom provided with jet openings disposed with their axes inclined to the plane of the pulp-supporting surface of said bottom.

24. In a flotation cell, a bottom provided with jet openings disposed with their axes parallel to one another and inclined to the plane of the pulp-supporting surface of said bottom.

25. In a flotation cell having a suitable point of tailings discharge, and provided with an air plate forming the bottom of the cell, said plate having a plurality of openings with axes inclined upward toward the point of pulp discharge, and means for passing air or gas through the openings into the cell whereby the sands resting on the bottom are caused to migrate toward the point of tailings discharge.

26. In a flotation cell, a perforated air plate, and means in the perforations for cleaning the walls of the perforations.

27. In a flotation cell, a perforated air plate, and mechanical devices in the perforations for cleaning said perforations.

28. In a flotation cell having a perforated bottom, reciprocating pins traversing the perforations and spaced from the walls thereof, and collars on the pins operating to rub the walls of the perforations to clean the same.

29. A flotation cell having a bottom provided with openings, and reciprocable cleaning devices in the openings for cleaning the same.

30. In a flotation cell having a perforated bottom. reciprocating pins traversing the perforations during the passage of the air therethrough.

31. In a. flotation cell having a perforated bottom, reciprocating pins traversing the perforations and forming with the Walls thereof suitable passage-ways for air or gas.

32. In a flotation cell provided with a bottom having a plurality of air openings, an air chamber below the bottom, a pin support in said chamber, pins on the support extending into the openings of the cell bottom, and means for reciprocating the pins for cleaning the air openings at any stage of the concentrating operation.

33. In a flotation cell provided with a bottom having a plurality of air openings, an air chamber below the bottom, a pin support in said chamber, pins on the support extending into the openings of the cell bottom and forming with the walls thereof suitable passageways for the air, and means for reciprocating the pins for cleaning the air openings at any stage of the concentrating operation.

34. In a flotation cell having a perforated bottom, movable pins permanently traversing the perforations.

35. In a flotation cell having a perforated bottom, movable pins traversing the perforations and forming with the walls thereof suitable passage-ways for air or gas.

36. In a flotation cell provided with a bottom having a plurality of air openings, an air chamber below the bottom, a pin support in said chamber, pins on the support extending into the openings of the cell bottom and traversed by the air in itspassage through said openings, and means for moving the pins forcleaning the air openings at any stage of the operation.

37. In a flotation cell provided with a bottom having a plurality of air openings, an air chamber below the bottom, a pin support in said chamber, pins on the support extending into the openings of the cell bottom and forming with the walls thereof suitable passage-ways for the air, and means for moving the pins for cleaning the air openings .at any stage of the operation.

In testimony whereof I affix my signature, in presence of two witnesses.

FRANK E. MARCY. IVitnesses Ronnn'r E. MARK, VIOLA P. DRUSHAL. 

